Self‐template hydrothermal synthesis ZnS microspheres

Zinc sulfide (ZnS) microspheres were synthesized by a self‐template hydrothermal route using thiourea as sulphur source. The formation of these hollow spheres was mainly attributed to the oriented aggregation of ZnS nanocystals around the gas‐liquid interface between gas (H₂S, NH₃, or CO₂) and water followed by an Ostwald ripening process. The gas bubbles of H₂S, NH₃, or CO₂ produced during the reaction might play a soft‐template to form ZnS hollow microspheres. The products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), electron diffraction (ED), and photoluminescence (PL). The crystal structure of prepared ZnS microspheres is hexagonal phase polycrystalline. The average microspheres diameter is 1.5 ‐ 6 µm. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Controllable synthesis of EuCO3OH microspheres and their thermal conversion to Eu2O3

EuCO₃OH microspheres have been successfully prepared using a facile hydrothermal approach, by using urea as the precipitant without the assistance of any surfactants or templates. Several experimental parameters were examined, such as the reaction temperature, the reaction time, and the molar ratios of the starting reagents. The Eu₂O₃ microspheres have been prepared by thermal conversion of EuCO₃OH microspheres at 800 °C in air for 6 h. The as‐obtained products were characterized by X‐ray diffraction, scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetry–differential thermal analysis and photoluminescence. The possible growth process for the EuCO₃OH microspheres was discussed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Controlled synthesis of selenium of different morphologies at room temperature

A facile and convenient chemical precipitation route has been developed for the controlled growth of selenium nanowires and hierarchical microspheres at room temperature, with Na₂SeO₃ and hydrazine hydrate as starting materials in the presence of 1,2,3‐trimethylimidazolium tetrafluoroborate (tmimBF₄). The surface morphology of microspheres can be tuned by adjusting the reaction media. The products were characterized by X‐ray powder diffraction (XRD) and scanning electron microscope (SEM). Possible formation mechanisms of selenium nanowires and microspheres are proposed, respectively. The influences of the nature of reaction media, agitation and tmimBF₄ on the morphologies development were experimentally investigated and it was found that these factors were of great importance for the formation of Se morphologies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stability of ruthenium nanoparticles synthesized by solvothermal method

One of the major obstacles to the synthesis of nanoparticles and nanocatalyst is the stability of particles. In the present study, polymer stabilized ruthenium nanoparticles were synthesized by solvothermal method using solutions of ruthenium chloride in ethylene glycol in presence of poly(N ‐vinyl‐2‐pyrrolidone) (PVP) as a stabilizing agent. Stability of nanoparticles was studied by varying different parameters e.g. PVP/RuCl₃ molar raio, RuCl₃ concentration, reaction temperature and time and expressed in terms of particle size and size distribution. Transmission electron microscope (TEM) analysis revealed the presence of metallic clusters with a uniform size of about 20‐65 nm. Dispersion destabilisation of colloidal nanoparticles was detected by Turbiscan. Polymer stabilized ruthenium nanoparticles were dispersed on γ‐alumina to prepare uniformly disperse Ru/γ‐Al₂O₃ catalyst by mechanical strirring and sonication. Inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), X‐Ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Thermo gravimetric analysis (TGA) were used to characterize the supported catalyst. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of post treatment on the photorefractive properties of Ru‐doped lithium niobate

The effect of post treatment on the photorefractive properties of Ru‐doped lithium niobate was studied. The absorption spectra examination of Ru‐doped LiNbO₃ crystals with different post treatments showed that the absorption coefficient at 530 nm increased after the reduced treatment was employed and the absorption edge of the reduced crystal shifted towards the infrared band. On the contrary, the trend reversed after the oxidized treatment was employed. In addition, the photorefractive properties were investigated with the two‐beam coupling method conducted via a 532 nm solid state laser. It was found that the oxidized Ru:LiNbO₃ had smaller exponential gain coefficient and diffraction efficiency because the charges in the shallow level were exchanged to the deep level. On the other hand, the reduced Ru:LiNbO₃ crystals had larger exponential gain coefficient and diffraction efficiency due to the increase of the Ru³⁺ which existed in the shallow level. The response times of both oxidized and reduced Ru:LiNbO₃ were longer than those of the as‐grown ones. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

One‐step fabrication of SnxTi1‐xO2 rutile‐type core‐shell microspheres and their electrochemical properties

Sn_xTi_1‐xO₂ core‐shell microspheres were synthesized through a simple one‐step hydrothermal method. The structural and morphologic properties were unambiguously characterized, and the electrochemical performance of the Sn_xTi_1‐xO₂ microspheres was determined by cyclic voltammetry. The possible formation mechanism of Sn_xTi_1‐xO₂ microspheres was also proposed.     

Hydrothermal synthesis of CdSe hierarchical microspheres

CdSe hierarchical microspheres have been successfully synthesized by a hydrothermal route at 120 °C for 16 h via a reaction between CdCl₂ and Na₂SeSO₃ in ionic liquid (1‐butyl‐3‐methylimidazolium bromide)‐water mixed medium. The structure and morphology of the as‐prepared products have been investigated by XRD and SEM, and the results indicate that the CdSe hierarchical microspheres have wurtzite structures and are self‐assembled by nanorods. It has been found that ionic liquid, reaction temperature, and reaction time have influence on the morphology of the products. The possible growth mechanism of CdSe with special morphology has been discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Investigation on the blue photorefractive properties varied with MgO codoping in Ru:Fe:LiNbO3 crystals

Mg:Ru:Fe:LiNbO₃ crystals with various doping concentration of MgO have been grown by Czochralski method. The type of charge carriers and photorefractive properties in Mg:Ru:Fe:LiNbO₃ crystals were measured by two‐wave coupling method using Kr⁺ laser (476 nm) and He‐Ne laser (633 nm) as light sources. We found that holes were the dominant charge carriers under blue light irradiation while electrons were the dominant charge carriers under red light irradiation. Mg²⁺ ions behaved no longer as damage resistant, but promoter to the photorefractive properties at 476 nm wavelength. The photorefractive properties under blue light improved with the increase concentration of Mg²⁺ ions. The enhancement mechanisms of the blue photorefractive were suggested. Experimental results definitely showed that Mg‐doped two‐centre Ru:Fe:LiNbO₃ was a promising blue photorefraction material for holographic volume storage.     

Morphological evolution of selenium micro‐crystals

A simple solution phase approach using dimethyl formamide (DMF) as solvent is utilized to obtain selenium (Se) microcrystals. Different morphological modifications of the products result from varied reaction environments. Solvothermal treatment of Se with DMF in an autoclave at 170°C yields rod‐like, and feather‐shaped microcrystalline structures while reduction of selenium dioxaide (SeO₂) by DMF generates microspheres at 30°C and 80°C, rods admixed with spherical particles at 120°C and predominantly micro rods at 150°C. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Highly efficient photocatalytic degradation of methyl orange and Rhodamine B by hierarchical BiOBr microspheres

Hierarchical BiOBr microspheres were successfully synthesized via a solvothermal method by using the diethylene glycol(DEG) as the solvent and soft‐template. The as‐obtained products were characterized by X‐ray powder diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM), N₂ adsorption–desorption and UV–Vis diffuse reflectance spectroscopy(DRS) techniques. The formation mechanism for the growth of hierarchical BiOBr microspheres has been studied. The possible mechanism of photocatalysis has been discussed. Remarkably, the as‐prepared BiOBr microspheres has a large specific surface area, which can reach a maximum surface area of 55.9307 m²/g. In addition, the superior enhanced photocatalytic activities of BiOBr microspheres were evaluated by the photodegradation of methyl orange (MO) and Rhodamine B (RhB) under visible‐light illumination, which presented the efficiency up to 98.10% just within 50 min and 98.64% within 30 min, respectively. BiOBr microspheres can be a promising candidate as highly efficient photocatalyst for decompositing of organic contaminants for environmental remediation.     

X-ray and neutron diffraction studies of the hydridotriruthenium cluster complex (μ-H)Ru3(CO)7(μ-As(C6H5)CH2As(C6H5)2) ((C6H5 2AsCH2As(C6H5)·CH2Cl2: an example of dibridged metal-metal bond M(μ-H)(μ-X)M,involving a heavy bridgehead atom

The title compound is (μ-H)Ru₃(CO)₇(μ-As(C₆H₅)CH₂As(C₆H₅)₂)((C₆H₅)₂ AsCH₂As(C₆H₅)₂)·CH₂C1₂. Crystal data: monoclinic,P2₁/n, cell parameters (X-ray)a=12.82(2) Å,b=22.91(2) Å,c=17.83(2) Å, β=99.1(3)°; (neutron)a=12.94(1) Å, β=22.95(2)Å,c=17.93(3)Å,β=99.55(5)°. The structure was solved from X-ray data. FinalR indices areR(F)=0.051,R _w (F)=0.049 (X-ray);R(F)=0.064,R _w (F)=0.048,R(F ²)=0.072,R _w (F²)=0.088 (neutron). The complex is derived from Ru₃(CO)₈(dpam)₂ through reaction with hydrogen. The structure consists of a triangular array of metal atoms involving three metal-metal bonds[Ru(1)?Ru(2)=2.912(7)Å;Ru(1)?Ru(3)=2.829(3) A; Ru(2)?Ru(3)=2.845(6) Å]. The metal-metal edge Ru(1)?Ru(2) is supported by a bridging bis(diphenylarsino)methane ligand which lies in the equatorial plane. Activation of the second dpam ligand has generated the new face-bridging ligand unit μ-As(C₆H₅)CH₂As(C₆H₅)₂. In this unit, the bridgehead As atom spans over the Ru(1)?Ru(2) bond, while the second As atom is only bonded to Ru(3). The metal environment is achieved by CO ligands. The hydride ligand is bridging the Ru(1)?Ru(2) vector [Ru(1)?H=1.791(10) Å; Ru(2)?H=1.818(8) Å]. Geometric features of the dibridged Ru(μ-H)(μ-As)Ru bond are discussed.     

Structure and photoluminescence properties of SrWO4 3D microspheres synthesized by the surfactant‐assisted hydrothermal method

In this paper, we report large‐scale high‐quality SrWO₄ 3D microspheres synthesized in aqueous solutions under mild conditions with cetyl trimethyl ammonium bromide as a simple cationic surfactant. These crystals have been characterized by X‐ray diffraction, transmission electron microscopy and field emission scanning electron microscopy techniques. The crystal growth processes were employed to investigate the formation mechanism of SrWO₄ 3D microspheres. Room‐temperature photoluminescence indicated that the as‐prepared SrWO₄ 3D microcrystals had strong emission peaks at about 432 and 505 nm, respectively.     

Preparation of monodispersed aragonite microspheres via a carbonation crystallization pathway

Monodispersed calcium carbonate microspheres were prepared by carbonating a calcium acetate aqueous solution with CO₂ gas at a high pressure of 40 bar and a high temperature of 80 °C after 60 minutes of reaction. The products were characterized by X‐ray powder diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD pattern showed that the crystal polymorph of the as‐prepared monodispersed microspheres was aragonite. The SEM images also displayed needle‐like aragonite self‐organized into microsphere superstructure with diameters ranging from 5 to 15 μm. Analysis of the formation mechanism of the calcium carbonate microsphere superstructure revealed that the rod‐dumbbell‐sphere morphogenesis mechanism along with the phase transformation of vaterite to aragonite was responsible for the growth of the monodispersed aragonite microspheres. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structure of [Ru(phen)3](ClO4)2.(C2H5)2O

The title solvated complex, in which phen denotes 1,10‐phenanthroline, crystallizes in the monoclinic space group P2₁/n with a = 13.313 (3), b = 15.980 (3), c = 18.392 (4) Å, α = 96.76 (3)°, Z = 4, V = 3885.4 (14) ų, D_cal = 1.564 Mg m^‐3. The crystal is composed of racemic layers of complex cations, with the ether solvents located near, and the perchlorate anions sandwiched between, indicating the hydrophobic environment in the complex layer and the stacking interaction between the enantiomeric cations. The average length of the Ru‐N bonds is 2.064 (2) Å and the average ligand bite angle is 80.00 (7)°.     

Room‐temperature synthesis and characterization of cross‐like Pr2(C2O4)3·10H2O micro‐particles

Cross‐like Pr₂(C₂O₄)₃·10H₂O micro‐particles were synthesized through a simple precipitation method at room temperature. The products were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), field‐emission scanning electron microscopy (FESEM), thermogravimetry–differential thermal analysis (TG‐DTA) and photoluminescence (PL). The possible formation mechanism of the cross‐like Pr₂(C₂O₄)₃·10H₂O micro‐particles was discussed, and Pr₆O₁₁ with similar morphology was obtained by calcining the oxalate precursor. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of polymerizing agent on structure and spectroscopic properties of nano‐crystalline La0.8Sr0.2MnO3 powders

Strontium‐doped lanthanum manganite (La_1‐xSr_xMnO₃ or LSM) is the material most widely used on solid oxide fuel cells cathode. In this work, nano‐scale La_0.8Sr_0.2MnO₃ powders have been synthesized by polymeric precursor‐based methods using different polymerizing agents with the aim of evaluating the influence of this change in the final powder. The powders calcined at 700 °C for 2 h have been characterized by X‐ray diffraction (XRD), scanning electron microscopy (FE‐SEM) and Fourier transform infrared spectroscopy (FTIR) in order to investigate the quality of both synthesis routes. It is shown that the crystal structure and morphology of the particles are significantly dependent on the preparation conditions. Single phase and La_0.8Sr_0.2MnO₃ nano‐crystalline particles less than 30 nm were obtained using ethylene glycol as polymerizing agent. FTIR results have been indicated that only the powder obtained using gelatin presented small traces of hydroxyl groups on its surface. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Investigation on growth defects in Pb(Zn1/3Nb2/3)O3‐PbTiO3 crystals

Relaxor ferroelectric crystal (1‐x)Pb(Zn_1/3Nb_2/3)O₃‐xPbTiO₃ (PZNT) with x=0.07 (PZNT93/7) has been grown by the vertical Bridgman method from the high temperature solution of PZNT‐PbO system. The growth defects, such as nucleation core, inclusions, boundaries and particles, were investigated by optical microscope and scanning electron microscope. Sub‐structures were found in the flux inclusions and the lack of ZnO component in PZNT crystals was attributed to the existence of ZnO particles in the inclusions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

PSSS‐controlled synthesis of CaCO3 superstructures

Complex CaCO₃ superstructure can be easily synthesized by using poly (sodium 4‐styrenesulfonate) (PSSS) as a structure directing agent to direct the controlled precipitation of calcium carbonate from aqueous solution. The products were characterized by scanning electron microscopy (SEM), and powder X‐ray diffraction (XRD) analysis. The results revealed that the morphology of the products changed significantly with the increasing of the concentration of PSSS in solution, from rhombohedral particles to plate‐packed aggregates to spheres with smooth surface, to sponge‐like spheres and finally to complex spherical superstructure consisted of plate‐like sub‐units. We hypothesize that the observed sequential changes in morphology of CaCO₃ particles with added PSSS concentration may be due to the influence of PSSS on nucleation, growth and aggregation of CaCO₃ crystals. The formation mechanisms of CaCO₃ crystals with different morphologies were discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,morphology and structure of the dense (Y1‐xEux)2O3 spherical shape particles

The method to decrease of the porosity (densification) of crystalline spherical particles of the solid substitution solution, obtained by the method of precipitation from aqueous solution followed by low temperature crystallization of the amorphous intermediate product was proposed. The comparative analysis of morphology and structure of the particles before and after densification have been carried. It has been established that porosity of (Y_1‐xEu_x)₂O₃ particles has decreased 5 times compared to their initial state. It has been shown that densification process of the (Y_1‐xEu_x)₂O₃ spherical particles changes their morphology and structure: the size of the crystals doubles, the number and area of crystalline boundaries decrease, the intercrystalline spaces, which forming pores, are almost absent.     

X-ray diffraction studies oncis-[Ru(bpy)2(PMe3)Cl+][ClO4 −] andcis-[Ru(bpy)2{PMe2(o-tol)}Cl+][ClO4 −]; two ordered structures in thecis-bis(bipyridyl)chloro(phosphine)-ruthenium(II) series

The complexcis-[Ru(bpy)₂(PMe₃)Cl⁺][ClO₄ ^?] crystallizes in space group P2₁/c andcis-[Ru(bpy)₂{PMe₂(o-tol)]Cl⁺][ClO₄ ^?] crystallizes in space group $P\bar 1$ ; each is present as a racemate and neither structure suffers from disorder. The Ru?PMe₂(o-tol) bond length of 2.324(2)Å is slightly longer than the simple Ru?PMe₃ bond length of 2.310(2) Å.